The present invention pertains to apparatus for splicing the ends of a magnetic tape wound on a spool of the type used in endless tape cartridges.
Endless magnetic tape cartridges are becoming increasingly popular because of their compact size, and their characteristic capability of providing endless sound without requiring that the cartridge be flipped-over, or that the direction of tape advancement be reversed. While a number of cartridge designs exist for providing the endless tape feature, the most successful configuration is a cartridge having a single, centrally disposed spool with the tape wound thereon such that the innermost winding of tape is withdrawn from its position adjacent the spool's hub and guided in an intricate tape guide path past one or more apertures in the cartridge housing. Such apertures permit the necessary co-action between the tape and the capstan, pinch roller and magnetic head, mounted on a tape transport designed to receive the cartridge. After traversing the cartridge apertures, the tape is guided to a position for being wound back onto the spool as the outermost winding. An example of this type of cartridge configuration is disclosed in U.S. Pat. No. 3,420,461, entitled "Endless Magnetic Tape Cartridge," issued Jan. 7, 1969 to R. P. Cousino.
In the manufacture of such endless tape cartridges, the tape is wound onto the spool such that the end of the innermost winding of the tape protrudes from a position adjacent the spool hub for being spliced to the end of the outermost winding of the tape. Because of the unique characteristics of the movement of the tape within the cartridge, it is essential that the material used to splice the ends of the tape be extremely thin, i.e., foil-like, so as not to form a thickened portion on the continuous tape which might not pass smoothly at all points along the tape path, such as at the point of withdrawal of the innermost winding of the tape adjacent the spool hub. As an example, the splice must be formed by a material that has a thickness no greater than 0.50 mils, and preferably of a material that is as little as 0.25 mils thick.
Also, it is desirable in many manufactured cartridges to provide a means for automatically stopping the tape transport at the end of the recorded material. For this purpose, the splicing segment can be formed with a metallized, conductive surface, such as an aluminized surface on a synthetic backing. The conductive surface of the splicing segment is arranged to cooperate with electrical contacts carried by the tape transport. When the segment reaches the contacts, the conductive surface forms a short circuit across the contacts, signalling the transport to stop the advancement of the tape.
Opposite the metallized, conductive surface, the splicing segment is usually coated with a contact adhesive. After cutting the segment to size, it is positioned to overlap abutting ends of the magnetic tape and the adhesive surface of the segment is pressed into adhering contact with the magnetic recoding surfaces (e.g., oxide surfaces) of the tape ends.
The foregoing characteristics of the splicing material, namely its ultra thinness, its metallized surface on one side and its contact adhesive coating on the other side, result in a foil-like material that is prone to wrinkle, fold and stick to itself and tear. When so deformed the splicing segment becomes unsuitable for forming a smooth, flat splice when placed on the magnetic tape. Furthermore, since the width of the magnetic tapes may be as little as one-eighth inch, the foil-like splicing material must be cut into individual splicing segments of this small width and then transported to the ends of the magnetic tape that are to be spliced. One manner of carrying out this operation is as follows. The splicing material is supplied in the form of a tape roll from which the splicing tape is withdrawn and cut into the proper size for the individual splicing segments, wherein each such prepared segment is temporarily retained on a sheet of transfer material, with the adhesive side down, ready for being manually removed, such as by tweezers, and applied to the magnetic tape. The procedure of manually transferring the individual splicing segments to the magnetic tape ends is at best, tedious and time consuming. Furthermore, the procedure typically results in a large percentage of defective splices, due to wrinkles in or other deformities of the splicing segment, or misalignment between the splicing segment and the magnetic tape. In such cases, the entire spool of magnetic tape must be discarded. The labor intensive transfer operation together with the large wastage factor, result in a relatively high per unit cost of the completed product.
In light of the above shortcomings of manual transfer techniques, attempts have been made to automate the splice segment cutting and transfering operations. One such attempt uses a cutter die and a cooperating apertured plate arranged so that the splicing tape is passed between the cutter die, which reciprocates vertically, and the apertured plate, which underlies the die, and so that the ends of the magnetic tape which are to be spliced are disposed immediately beneath the aperture in the plate. On the down stroke of the cutter die, the splicing tape is cut (i.e., blocked out) to the size of the die and aperture, and then forced by the continuing downward stroke of the die onto the underlying magnetic tape ends. While this technique works for relatively thick splicing tape (i.e., greater than 0.5 mils) it has proved completely unsatisfactory for foil-thin splicing tapes (i.e., less than 0.5 mils) because achievable tolerances of the cutter die and apertured plate do not mate closely enough to consistently sever the splicing tape at all points around the perimeter of the die and aperture. Furthermore, even if the splicing segment is cleanly cut, it tends to be easily deformed as it is pushed toward the magnetic tape ends during the ensuing downward movement of the cutter die.
Accordingly, it is an object of the invention to provide an automated or semiautomated apparatus for splicing the ends of the magnetic tape wound on spools of the type used in endless tape cartridges.
A more particular object is to provide such apparatus which automatically prepares and handles individual segments of foil-thin splicing tape of the type having a contact adhesive on one surface, in order to eliminate the most tedious and difficult phase of the splicing operation.
A further object is to provide such an apparatus having the desirable features of reducing the labor time involved in splicing each spool of tape, and at the same time reducing the amount of material wastage resulting from the formation of defective splices.